CN1230050C - Electronic machine - Google Patents

Abstract

To provide highly reliable in-vehicle electronic equipment that prevents conductor wiring from corroding. On substrates made of composite materials of ceramics, resins and inorganic parts, and resin parts, the corrosion resistance can be improved by coating the surface of the conductor wiring used to form a circuit formed by printing or bonding with glass, resin, or solder and silver. It can provide highly reliable in-vehicle electronic devices. In addition, the adjustment part required for resistance value and characteristic adjustment is used for the shape of the mounting part of the mounting part, such as a circle or an ellipse without corners less than 90°, and R, C are set on the corners of the quadrangle. shape.

Description

electronic machine

technical field

The present invention relates to electronic equipment, and particularly relates to a sealing structure of various sensors that output various physical quantities as electrical signals through sensor elements that detect various physical quantities and electronic circuits that control the above-mentioned sensor elements, which are installed in the engine compartment, And an electronic circuit mounting structure related to improving corrosion resistance of electronic equipment for vehicles with a microprocessor computer that receives electrical signals from the above-mentioned various sensors to control various states of the vehicle.

Background technique

Various hybrid IC substrates are known that consist of printing thick-film resistors on a ceramic substrate and mounting components such as semiconductor integrated circuits, capacitors, and diodes. Among them, for hybrid IC substrates using silver, silver alloys, copper, and copper alloys in conductor wiring, especially for hybrid IC substrates used in automotive electronic equipment, due to the threat of corrosion of conductor wiring by corrosive gases, As a countermeasure to improve corrosion resistance, the method of enclosing the conductor wiring with glass or the like is considered, but since there are differences in the resistors printed on the hybrid IC substrate and the mounted electronic components, in order to provide high-precision electronic devices, adjustments are required For resistance value, characteristics, etc., it is necessary to have a conductor exposed part for adjustment. As a method of covering this exposed portion, solder is generally used, but the purpose is not to improve corrosion resistance, but it is limited to the place where adjustment is required in consideration of contact during adjustment. In addition, even when solder is provided, the spreadability of the solder is poor, and there are many exposed parts of the conductor wiring. As a measure to improve the solder smearability, a process improvement method such as two-dimensional firing is adopted as described in JP-A-4-334083.

In the prior art, the conductor wiring constituting the circuit was not coated, and the corrosion resistance could not be satisfied due to environmental reasons. In addition, even if it is coated with solder, since the coating property of solder is poor, the ends, especially the corners, of the conductor wiring and the mounting part of the mounting part are exposed, and the corrosion resistance cannot be satisfied.

Contents of the invention

An object of the present invention is to improve corrosion resistance without impairing the function of the electronic circuit even if the opening is corroded.

The present invention achieves the above objects. For example, in electronic equipment, in order to solve the above-mentioned problem of corrosion resistance, in order to adjust the resistance value and adjust the characteristics, the opening part of the glass or resin coating is provided with a structure covered with solder or metal paste, and the resistance can be improved. corrosive. In addition, the corrosion resistance can be improved by setting the shape of the opening to, for example, a circle or an ellipse without corners of 90° or less, or by providing R and C shapes at the corners of a quadrangle.

In addition, by branching the opening from the lead wire constituting the circuit or forming conductors in parallel, even if the opening is corroded, the function of the electronic circuit can be improved without impairing the corrosion resistance.

Description of drawings

FIG. 1 is a sectional structural view of an in-vehicle electronic device showing the features of the present invention.

FIG. 2 is an example of an environment in which in-vehicle electronic devices are placed.

Fig. 3 is a structural diagram of a thermal flow measuring device.

Fig. 4 is a cross-sectional structural view of a thermal flow measuring device.

Fig. 5 is a diagram showing the structure of an electronic circuit board.

Fig. 6 is an example of an electronic circuit board probe section.

Fig. 7 is an example of an electronic circuit board probe section.

Fig. 8 is an example of an electronic circuit board probe section.

FIG. 9 is an example of an electronic circuit board probe portion.

Fig. 10 is an example of an electronic circuit board probe section.

Fig. 11 is an example of an electronic circuit board probe section.

Fig. 12 is an example of an electronic circuit board probe section.

Fig. 13 is an example of an electronic circuit board probe section.

Fig. 14 is an example of an electronic circuit board probe section.

Fig. 15 is a cross-sectional structural view of an electronic circuit board.

FIG. 16 is an example of a probe portion of an electronic circuit board.

Fig. 17 is a cross-sectional structural view of an electronic circuit board.

Fig. 18 is a cross-sectional structural view of an electronic circuit board.

Detailed ways

First, FIG. 1 shows a representative cross-sectional view of an in-vehicle electronic device that is exposed to a severe corrosion environment as the electronic device. In addition, using Fig. 2 showing the corrosive environment in which in-vehicle electronic equipment is exposed, the structure, operating environment and problems of in-vehicle electronic equipment will be explained. Vehicle-mounted electronic devices are roughly divided into fuel control devices for sensors and control units, and ignition control devices for igniters and coils. The sensor detects physical quantities such as intake air flow, air temperature, atmospheric pressure, and boost pressure. The control unit receives the signal from the sensor and has the function of controlling the combustion state in the cylinder. The igniter and coil are responsible for controlling the ignition time inside the cylinder. Most of these common structures in the structure of vehicle-mounted electronic devices are that each electronic drive circuit 1, or electronic control circuit, is glued and fixed on the metal base 2 on which the electronic drive circuit 1 or electronic control circuit is provided, and the The casing 3 storing the above-mentioned electronic drive circuit 1 or the electronic control circuit is glued and fixed 4 on the base 2 , and the upper surface is glued and fixed 6 with a cover 5 . The above-mentioned electronic drive circuit 1, or the electronic control circuit is formed by printing the conductor wiring 8 and the resistance firing as the circuit conductor on the surface of the planar substrate 7 formed by inorganic materials such as ceramics, and adopts the method of mounting on the surface more often. The hybrid IC substrate 9 in the form of a capacitor, a diode, or a semiconductor integrated circuit is bonded to the metal base 2 with a silicon adhesive in order to promote heat dissipation of the hybrid IC substrate 9 . Since the metal base 2 serves as a heat sink for heat dissipation, a metal with high thermal conductivity, especially aluminum, is often used. The case 3 for accommodating the hybrid IC substrate 9 and the cover 5 covering the top are integrally shaped with the terminals that serve as the input and output signal interfaces of the electronic drive circuit 1, and are usually inserted into the resin forming the case 3 to form a circuit board for electrical signals. The structure of the terminal 11 is composed of the conductive parts of the transfer. Here, the sensor for detecting physical quantities such as intake air temperature, intake air flow rate, boost pressure, etc. is configured by placing the sensing element 10 outside or on the opening of the case, and electrically connecting with the electronic drive circuit 1 via the terminal 11 . The housing 3 is glued and fixed 4 on the base 2 , and the cover 5 is also glued and fixed 6 on the shell 3 . As the resin material for forming the case 3 and the cover 5, polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), nylon-6, nylon-66, nylon- 11. Nylon-12 and other resins with excellent injection moldability.

Here, since the aforementioned resin case 3 and metal base 2 have a large difference in linear expansion coefficient, they are bonded and sealed with an elastic adhesive having viscoelasticity such as silicon adhesive 12 in many cases. In addition, if the shell 3 and the cover 5 are the same part, epoxy adhesive is often used, and if they are different parts, silicon adhesive is often used to seal.

The in-vehicle electronic devices described above often use adhesive bonding for the bonding of structural parts, and are characterized in that silicon adhesive 12 is often used.

However, the silicone adhesive 12 has disadvantages due to properties specific to silicone resins. The inside of the engine compartment of a vehicle equipped with in-vehicle electronic equipment is exposed to gaseous atmosphere 13 where hydrocarbons remain due to backflow of combustion gas from the engine and return of unburned gas. In addition, the inside of the engine room is in a state where many parts such as rubber pipes containing sulfur and hoses arranged in the engine components are concentrated, and the temperature of the electronic equipment inside the engine is also in a state of exceeding 100°C. In this state, sulfur gas, or sulfur compound gas 14 , will be gushed out from rubber conduits, hoses, and other components made of sulfur by vulcanization. In addition, these sulfur gases migrate in the environment and become a composite gas state mixed with the above-mentioned backflow of combustion gas, return gas of unburned gas, hydrocarbon 13, etc. according to different occasions. In-vehicle electronic equipment without the capability may not be able to obtain products with high reliability. This is because the conductor wiring 8 formed on the flat substrate 7 of many electronic drive circuits 1 in these in-vehicle electronic devices is mostly formed of silver or silver alloy, and corrosive gas, especially sulfur gas, enters the inside of the housing 3. , sulfur compound gas 14, the silver, silver alloy, copper, copper alloy wiring that becomes the conductor wiring 8 is partially corroded, the conductor wiring 8 of the electronic drive circuit 1 is disconnected, and the electronic drive circuit 1 may not work normally. Because of the state of work. Since the sulfide corrosion of the conductor wiring 8 starts from the exposed portion of the conductor wiring 8, it has been proposed to improve the performance of protecting the electronic drive circuit 1 in corrosive gases by covering the exposed portion with glass, resin, solder, or metal paste. Solutions for in-vehicle electronic devices.

The sulfidation corrosion resistant structure of the electronic device of the present invention will be described below.

There are many kinds of electronic equipment, and it is difficult to explain all of them here. Therefore, as a typical electronic equipment, the thermal flow measuring device for measuring the intake air flow rate shown in FIG. Example. First, a thermal flow measuring device will be briefly described. 3 and 4 are sectional structural views showing the structure of the thermal flow measuring device. In each figure, 19 denotes a sub-path, 20 denotes an intake air temperature sensor, 21 denotes an adjustment part, 22 denotes a conductor wiring exposed part, 23 denotes a resistor, and 27 denotes solder. Thermal flow measuring devices are sensors that measure intake air. The heating resistor 15 of the thermal air flowmeter 17 using the heating resistor 15 and the temperature-sensing resistor 16 is controlled by a constant temperature control circuit 18 so as to maintain a certain temperature difference with the temperature-sensing resistor 16 for measuring the air temperature. The structures of the heating resistor 15 and the temperature sensing resistor 16 are arranged in the air filter through which the air sucked into the engine flows, or in the air passage downstream of the air filter, and are embedded in the constant temperature control system. The electric circuit 18 and the conductive member 11 in the housing 3 perform electrical signal transmission. In the thermal flowmeter measurement device described above, the base 2 for dissipating self-heating of power devices such as power transistors serves as a structural base. On the above-mentioned base 2, on the surface of the plane substrate 7, or on the back surface, the conductive wiring 8 and resistors are formed by printing, and then the semiconductor integrated circuits, power transistors, capacitors, inductors, and diodes are bonded and installed with silicon adhesives. and other hybrid IC substrates 9 . Furthermore, the structure is that the case 3, which serves as a base body for accommodating the hybrid IC substrate 9, and at the same time is formed with a terminal for transmitting the sensor signal to the outside, or an interface part for supplying circuit driving power from the outside, is bonded with a silicon adhesive 12. It is sealed on the base 2, and then the upper surface of the case 3 is covered with a cover 5, and sealed with a silicon adhesive, an epoxy adhesive, or the like. On the hybrid IC substrate 9, the printed resistors and conductor wiring 8 are coated with glass, resin, etc., but in order to adjust the resistance value of the printed resistors, and to adjust the characteristics of the output, etc., it is necessary to install and conductor wiring. The line 8 is electrically connected to the debugging part that can be debugged, and the probe is brought into contact with the debugging part to perform adjustments such as characteristics. As described above, the silicon adhesive 12 used for bonding many parts and parts is in a highly gas-permeable and corrosive environment, and the corrosive gas permeates inside the case 3 compared with the adhesive fixing 4 . In addition, corrosive gas enters through the vent holes provided at the terminals of the case 3 . Therefore, in order to prevent the conductor wiring 8 and the mounting parts of the hybrid IC substrate 9 inside the case 3 from being corroded, the debugging part required for adjustment provided on the hybrid IC substrate 9 or the conductor wiring exposed part are worked hard. , To prevent the corrosion of the conductor wiring 8 by the corrosive gas, it is possible to manufacture an electronic machine with high corrosion resistance and reliability, including a thermal flow measuring device.

Specifically, by coating the debugging portion of the hybrid IC substrate 9 with solder, metal paste, etc., the contact between the corrosive gas and the conductor wiring 8 can be reduced, and the corrosion resistance can be improved. In addition, the same effect can be obtained by coating the conductor wiring exposed part with glass or resin after adjustment of resistance value and characteristics.

Here, when the debug section is provided on the hybrid IC substrate 9, it is effective to provide an opening on the overcoat layer of glass or resin, and coat the opening with conductive metal such as solder or metal paste. In some cases, if the applicability of solder, metal paste, etc. to the conductor wiring is poor, the end, especially the conductor wiring at the corner will be exposed, because it may be corroded by corrosive gas, so by using solder or metal paste coating The surface shape of the coating is set to a shape without corners below 90 degrees, such as a circle, an ellipse, a shape with R (arc shape) or C (cone shape) at the corners of a quadrilateral, which can reduce conductor wiring The exposure of the end corners can improve the corrosion resistance. In the case of a quadrilateral, it is desirable that the ratio of the short side to the long side is 0.5 to 1.5, and R and C at the corners are set to R0.1 to 0.5 and C0.1 to 0.5, respectively.

In addition, even in the mounting portion for mounting components such as capacitors, inductors, and diodes on the hybrid IC substrate 9, if the applicability of the metal paste is poor, the ends, especially the conductor wiring at the corners, are exposed, and there is a risk of It may be corroded by corrosive gas, so the corrosion resistance can be improved by making the corners of the conductor wiring exposed portion 22 for mounting components R or chamfering. At this time, it is desired that the size of R at the corner is R0.1~R0.5, and the size of the chamfer is C0.1~C0.5.

In addition, corrosion resistance can be improved by forming conductor wiring under components such as capacitors, inductors, and diodes to be mounted.

In addition, in the debugging part or the mounting part, by forming a conductor pattern branched from the conductor line or forming conductors in parallel, the function of the electronic circuit will not be impaired even if the wire is partially disconnected, thereby improving corrosion resistance. In the case of forming conductor wiring in two or more layers, by connecting the upper and lower parts of the adjustment part with the conductor wiring 24 formed on the lower layer of an insulator 25 such as glass, the conductor wiring can be corroded even if the conductor exposed part is corroded. Corrosion resistance can be improved because the circuit configuration can be maintained through the lower layer connection.

In addition, since the outermost conductor wiring 26 formed on the outer side of the ceramic substrate 9 has many chances of applying stress in the actual use state during the manufacturing stage, it is easier to damage than the conductor wiring formed on the inner side. Corrosion resistance can be improved by making the outermost conductors wider than the inner conductors. Corrosion resistance can be further improved by setting the width of the outermost conductor to be at least twice the width of the inner conductor.

According to the present invention, corrosion of conductor wiring can be prevented from exposure to a corrosion-resistant environment of a hybrid IC substrate.

Claims (14)

1. An electronic device in which a protective electronic substrate is built in a case member, and the electronic substrate includes an insulating substrate and an electronic circuit formed by forming a film-shaped conductor, a resistor, and a mounting part for a capacitor on the surface thereof, characterized in in: In the film-shaped conductor formed on the surface of the above-mentioned substrate, in the manufacturing process of the electronic device, except for the debugging part for obtaining electrical connection with the conductor, and the mounting part that becomes the connection part with the conductor of the above-mentioned mounting part , the above-mentioned film-shaped conductor is coated with glass or resin, that is, coating, and the uncoated openings of the above-mentioned debugging part and the installation part are all set in a circle, an ellipse without corners below 90°, or in a quadrilateral The corners are arranged in an arc or conical shape, surround the openings of these coating materials, and cover with solder or metal paste. 2. An electronic device in which a protective electronic substrate is built in a case member, and the electronic substrate includes an insulating substrate and an electronic circuit formed by forming a film-shaped conductor, a resistor, and a capacitor mounting part on the surface thereof, characterized in in: Most of the film-shaped conductors formed on the surface of the substrate are coated with glass or resin coating materials, and the remaining part is coated with conductive parts such as solder or metal paste. The surface shape of the layer portion is all provided in a circular or elliptical shape without corners of less than 90°, or in a shape of an arc or a cone at the corners of a quadrilateral. 3. The electronic device according to claim 1, wherein the shape of the solder or metal paste coating portion is a quadrilateral or an ellipse with a ratio of a long side to a short side in a range of 0.5 to 1.5. 4. The electronic device according to claim 1, wherein the shape of the solder or metal paste coating portion is a quadrilateral having an arc or a cone of 1/10 or more of the long side at the corner. 5. The electronic device according to claim 1, wherein the shape of said solder or metal paste coating portion is a quadrangular shape in which a 0.1 to 0.5 circular arc or conical shape is provided at a corner. 6. The electronic device according to claim 1, wherein the housing member is formed by combining a member having a conductive terminal for electrically connecting the electronic substrate in the housing to the outside of the housing, and a cover, and the joint is formed by Adhesion, welding, or joining via a sealing material serves as an airtight casing member. 7. The electronic device according to claim 1, wherein said conductor contains silver or copper as a main component. 8. The electronic device according to claim 1, wherein the insulating substrate is made of ceramics, the conductors and resistors are formed by thick film printing, and the coating is formed by thick film printing of glass. And solder is printed on the mounting portion, and after the mounting component is mounted, so-called reflow of heating and melting the solder is performed. 9. The electronic device according to claim 8, wherein the thickness of the printed film of the solder is more than five times the thickness of the coated glass film. 10. The electronic device according to claim 8, wherein the thickness of the printed film of the solder is more than five times the thickness of the printed film of the conductor. 11. The electronic device according to claim 8, wherein the solder contains lead or tin as a main component. 12. The electronic device according to claim 1, wherein said electronic device is a heating resistance type flow measuring device. 13. The electronic device according to claim 12, wherein the heating resistance type flow measuring device is a device for measuring the flow rate of air sucked into the automobile engine, and is installed on the air intake line. 14. The electronic device according to claim 12, wherein a part or the whole of the housing member which houses and protects the electronic substrate is located in the flow path through which the fluid to be measured flows.

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